Electric-current-shunting device.



R. W. W. GRIGSBY. ELECTRIC CURRENT SHUNTING DEVICE. APPLIOATION P-ILED 001'; 24, 1910.

1,008,326, Patented NOV. 14, 1911.

Witnesses Attorneys.

REDMAN W. W. GRIGSBY, OF LOS ANGELES, CALIFORNIA.

ELECTRIG-CURRENT-SHUNTING DEVICE.

Specification of Letters Patent.

Patented Nov. 14:, 1911.

Application filed October 24, 1910. Serial No. 588,775.

To all whom it may concern:

Be it known that I, REDMAN W. W. Gnics- BY, a citizen of the United States, residing at Los Angeles, in the county of Los Angeles and State of California, have invented a new and useful Electric-Current-Shunting Device, of which the following is a specification. 7

One of the objects of this invention is to provide a simple and eifective shunting means for reducing the quantity of electric current, in any desired ratio or proportion, for application to standard makes of commercial instruments having a relatively small quantity capacity.

Another object of the invention is to provide a simple and effective means for reduc ing the quantity of electric current, and transmitting the same to a watt meter, a circuit breaker, or the like, having a relatively small quantity capacity, the said means being unaffected by temperature changes within the device.

In the drawings,-Figure 1 shows the invention in side elevation, parts beingbroken away; Fig. 2 is a top plan; Fig. 3 is an end elevation.

The instrument includes an insulating base 1, provided with suitably positioned holes 14:, whereby the base may be secured to a support. This base 1 carries binding members adjacent its ends. One of these binding members consists of a block 2, of conducting material, and a post 1 threaded into the block. The other binding member consists of a block 3, fashioned from conducting material, and a post 5 threaded into the block 3. This preferred form of binding member, however, may be departed from, without jeopardizing the utility of the invention.

A primary resistance 6 is provided, consisting of a plurality of laminations 7. This primary resistance 6 is bent or looped upon itself, as clearly shown in Fig. 1. The secondary resistance 8 is ordinarily a plate or piece of metal, formed in a series of loops, the adjacent edges 10 of the segments 9 of the loops being parallel; the secondary resistance, in general outline, approximating the outline of the primary resistance. At one end, the secondary resistance 8 is electrically connected, as shown at 11, with the block 2 of one binding member. The other end of the secondary resistance is, as shown at 12, electrically connected with a head 15,

of conducting material. A sheet of insulation 16 is interposed between the head 15 and the block 8 of one binding member, and a screw 17 or other securing device, is extended through the head 15, and through the insulation 16, to engage the block. This securing member 17 is insulated from the head 15 by means of a collar 18, surrounding the securing member. The head 15 carries a binding post 19 or the like, adapted to receive an electric conductor. The block 3 has'a binding screw 21 or the like, whereby a conductor may be secured to the block.

The device is adapted to be interposed in an electric main, by connecting the terminals 20 of the main with the binding members 2-4, and 35. The binding element 21 in'the block 3 is adapted to receive a conductor 22 leading to an instrument, shown in the present instance in the form of a watt meter W. The binding element 19 is adapted to receive another conductor 23, connecting electrically with the watt meter W.

Threaded bolts 24 are slidably mounted between the edges 10 of the segments 9 of the secondary resistance 8. These bolts 24: carry nuts 26 at one end. Washers 27 are engaged between the heads of the bolts 24L and the secondary resistance 8 upon one side of the said resistance. Other washers are bound against the secondary resistance 8 bymeans of the nuts 26.

In connecting up a watt meter or the like with an electric main, the low primary resistance 6 ordinarily becomes heated after a brief use, increasing the resistance of the element 6, and consequently increasing the current strength flowing through the conductors 22 and 23, the watt meter, or other instrument, in such instance, indicating a stronger current than is actually flowing through the main 20. To overcome this difliculty, the secondary resistance 8 is provided; and at this point it should be noted that the primary resistance 6 and the secondary resistance 8 are so proportioned that, as the primary resistance 6 becomes heated, the secondary resistance 8 will be correspondingly heated; the resistances of the elements 6 and 8 being correspondingly increased, whereby the registering of the watt meter or the like, will be unaffected.

It will be seen that by loosening the bolts 24, and sliding the same between the segments 9 of the secondary resistance 8, portions of the secondary resistance may be short-circuited, and cut out, thus enabling the operator to adjust the ratio between the resistance 6 and the resistance 8.

Having thus described the invention, What is claimed is In a device of the class described, spaced binding members; a primary resistance between the binding members; a secondary resistance electrically connected With one binding member and secured to but insulated from, the other binding member; the secondary resistance consisting of a plurality of loops; slidable elements electrically connecting the adjacent portions of the loops to short-circuit portions of the secondary resistance; and means upon the last named binding member and the adjacent end of the secondary resistance, to receive the conductors from an instrument.

In testimony that I claim the foregoing as my own, I have hereto afliXed my signature in the presence of tWo Witnesses.

REDMAN N. W. GRIGSBY.

Witnesses:

A. A. GATES, J. O. BORLON.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

